Introduction to Experiment WA85

One of the most interesting predictions of QCD is the possibility that hadronic matter, under extreme conditions of density and/or temperature, will no longer exist in the familiar hadron phase form of baryons and mesons but will melt into a free gas of quarks and gluons. Such a phase of matter is known as a Quark-Gluon Plasma (QGP). When a QGP is produced the yields of strange and, particularly, multi-strange particle are increase.

The WA85 experiment was designed to study strange and multi-strange particle production in sulphur-tungsten interactions at 200 GeV/c per nucleon. Data from proton-tungsten interactions at 200 GeV/c were also taken as an experimental control.

The results from WA85 show that Lambda and anti-Lambda particles are enhanced by a factor of about 2.7 whereas the multi-strange Xi and anti-Xi hyperons are enhanced by a factor of about 3.8. These results suggest that a QGP could indeed be produced in these central sulphur-tungsten interactions.